<!DOCTYPE html>
<meta charset="utf-8">
<style>

.link {
  fill: none;
  stroke-width: 1.5px;
}

.axis, .node {
  stroke: #000;
  stroke-width: 1.5px;
}

</style>
<body>
<script src="../../d3.v2.js"></script>
<script src="link.js"></script>
<script>

var width = 960,
    height = 500,
    innerRadius = 40,
    outerRadius = 240;

var angle = d3.scale.ordinal()
    .domain(d3.range(4))
    .rangePoints([0, 2 * Math.PI]);

var radius = d3.scale.linear()
    .range([innerRadius, outerRadius]);

var color = d3.scale.category10()
    .domain(d3.range(20));

var nodes = [
  {x: 0, y: .1},
  {x: 0, y: .9},
  {x: 1, y: .2},
  {x: 1, y: .3},
  {x: 2, y: .1},
  {x: 2, y: .8}
];

var links = [
  {source: nodes[0], target: nodes[2]},
  {source: nodes[1], target: nodes[3]},
  {source: nodes[2], target: nodes[4]},
  {source: nodes[2], target: nodes[5]},
  {source: nodes[3], target: nodes[5]},
  {source: nodes[4], target: nodes[0]},
  {source: nodes[5], target: nodes[1]}
];

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
  .append("g")
    .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");

svg.selectAll(".axis")
    .data(d3.range(3))
  .enter().append("line")
    .attr("class", "axis")
    .attr("transform", function(d) { return "rotate(" + degrees(angle(d)) + ")"; })
    .attr("x1", radius.range()[0])
    .attr("x2", radius.range()[1]);

svg.selectAll(".link")
    .data(links)
  .enter().append("path")
    .attr("class", "link")
    .attr("d", link()
    .angle(function(d) { return angle(d.x); })
    .radius(function(d) { return radius(d.y); }))
    .style("stroke", function(d) { return color(d.source.x); });

svg.selectAll(".node")
    .data(nodes)
  .enter().append("circle")
    .attr("class", "node")
    .attr("transform", function(d) { return "rotate(" + degrees(angle(d.x)) + ")"; })
    .attr("cx", function(d) { return radius(d.y); })
    .attr("r", 5)
    .style("fill", function(d) { return color(d.x); });

function degrees(radians) {
  return radians / Math.PI * 180 - 90;
}

</script>
